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Electromagnetic Coupling in Star-Planet Systems

Living reference work entry

Abstract

Most exoplanets are expected to be embedded in the flows of plasmas and the magnetic fields of their host stars. This setup enables powerful electromagnetic coupling mechanisms if the exoplanets are sufficiently close to their host stars. The coupling can result in large electromagnetic energy fluxes between the exoplanets and the stars possibly generating luminous effects on the stars. The root cause of the electromagnetic interaction and the resulting coupling is the relative motion of the exoplanet with respect to the magnetized plasma of the host star. Due to the large diversity of the exoplanets, e.g., distance to star, size, and the diversity of the host stars, e.g., stellar classes, the nature and the energy fluxes in the star planet interaction are expected to exhibit huge quantitative and qualitative variability. In this chapter, we introduce the basic setup of this coupling and the underlying physical mechanisms. We discuss various models of the electromagnetic coupling, such as the Alfvén wing model or models which describe the release of magnetic stresses, e.g., in coronal magnetic fields. We also briefly review the existing observational evidence for the star planet coupling and put it in context with theoretical expectations. We also compare the star planet coupling with the well-studied electromagnetic coupling between planets and moons in the outer solar system, e.g., Jupiter and its moon Io.

References

  1. Acuña MH, Ness NF (1980) The magnetic field of Saturn – Pioneer 11 observations. Science 207:444–446ADSCrossRefGoogle Scholar
  2. Alvarado-Gómez JD, Hussain GAJ, Cohen O et al (2016) Simulating the environment around planet-hosting stars. II. Stellar winds and inner astrospheres. A&A 594:A95Google Scholar
  3. Baumjohann W, Treumann RA (1996) Basic space plasma physics. Imperial College Press, LondonCrossRefMATHGoogle Scholar
  4. Bonfond B, Grodent D, Gérard J et al (2008) UV Io footprint leading spot: a key feature for understanding the UV Io footprint multiplicity? Geophys Res Lett 35:L05,107CrossRefGoogle Scholar
  5. Chané E, Saur J, Neubauer FM, Raeder J, Poedts S (2012) Observational evidence of Alfvén wings at the Earth. J Geophys Res (Space Phys) 117(A16):A09217ADSGoogle Scholar
  6. Chané E, Saur J, Poedts S, Keppens R (2017) How is the Jovian Main auroral emission affected by the solar wind? J Geophys Res (Space Phys) 122:2016JA023,318Google Scholar
  7. Clarke JT, Ajello J, Ballester GE et al (2002) Ultraviolet emissions from the magnetic footprints of Io, Ganymede and Europa on Jupiter. Nature 415:997–1000ADSCrossRefGoogle Scholar
  8. Cohen O (2017) A comparison between physics-based and polytropic MHD models for stellar coronae and stellar winds of solar analogs. ApJ 835:220ADSCrossRefGoogle Scholar
  9. Cohen O, Drake JJ, Kashyap VL et al (2009) Interactions of the magnetospheres of stars and close-in giant planets. ApJ 704:L85–L88ADSCrossRefGoogle Scholar
  10. Cohen O, Kashyap VL, Drake JJ et al (2011) The dynamics of stellar coronae harboring hot Jupiters. I. A time-dependent magnetohydrodynamic simulation of the interplanetary environment in the HD 189733 planetary system. ApJ 733:67Google Scholar
  11. Connerney JEP, Baron R, Satoh T, Owen T (1993) Images of excited H3 + at the foot of the Io flux tube in Jupiter’s atmosphere. Science 262(5316):1035–1038ADSCrossRefGoogle Scholar
  12. Cuntz M, Saar SH, Musielak ZE (2000) On stellar activity enhancement due to interactions with extrasolar giant planets. ApJ 533:L151–L154ADSCrossRefGoogle Scholar
  13. Elsässer W (1950) The hydromagnetic equations. Phys Rev 79:183ADSCrossRefMATHGoogle Scholar
  14. Goertz CK (1980) Io’s interaction with the plasma torus. J Geophys Res 85(A6):2949–2956ADSCrossRefGoogle Scholar
  15. Goldreich P, Lynden-Bell D (1969) Io, a Jovian unipolar inductor. Astrophys J 156:59–78ADSCrossRefGoogle Scholar
  16. Gurdemir L, Redfield S, Cuntz M (2012) Planet-induced emission enhancements in HD 179949: results from McDonald observations. PASA 29:141–149ADSCrossRefGoogle Scholar
  17. Ip WH, Kopp A, Hu J (2004) On the star-magnetosphere interaction of close-in exoplanets. Astrophys J 602:L53–L56ADSCrossRefGoogle Scholar
  18. Jacobsen S, Neubauer FM, Saur J, Schilling N (2007) Io’s nonlinear MHD-wave field in the heterogeneous Jovian magnetosphere. Geophys Res Lett 34:L10,202. doi:10.1029/2006GL029187 CrossRefGoogle Scholar
  19. Kivelson MG, Bagenal F, Neubauer FM et al (2004) Magnetospheric interactions with satellites, Chap. 21 In: Bagenal F (ed) Jupiter. Cambridge University Press/University of Colorado, Cambridge, pp 513–536Google Scholar
  20. Kopp A, Schilp S, Preusse S (2011) Magnetohydrodynamic Simulations of the magnetic interaction of hot Jupiters with their host stars: a numerical experiment. Astrophys J 729:116ADSCrossRefGoogle Scholar
  21. Lanza AF (2008) Hot Jupiters and stellar magnetic activity. Astron Astrophys 487:1163–1170ADSCrossRefGoogle Scholar
  22. Lanza AF (2009) Stellar coronal magnetic fields and star-planet interaction. A&A 505:339–350ADSCrossRefMATHGoogle Scholar
  23. Lanza AF (2012) Star-planet magnetic interaction and activity in late-type stars with close-in planets. A&A 544:A23ADSCrossRefGoogle Scholar
  24. Lanza AF (2013) Star-planet magnetic interaction and evaporation of planetary atmospheres. A&A 557:A31ADSCrossRefGoogle Scholar
  25. Lanza AF (2015) Star-planet interactions. In: van Belle GT, Harris HC (eds) 18th Cambridge workshop on cool stars, stellar systems, and the sun, Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, vol 18, pp 811–830Google Scholar
  26. Neubauer FM (1980) Nonlinear standing Alfvén wave current system at Io: theory. J Geophys Res 85(A3):1171–1178ADSCrossRefGoogle Scholar
  27. Neubauer FM (1998) The sub-Alfvénic interaction of the Galilean satellites with the Jovian magnetosphere. J Geophys Res 103(E9):19,843–19,866ADSCrossRefGoogle Scholar
  28. Olson P, Christensen UR (2006) Dipole moment scaling for convection-driven planetary dynamos. Earth Planet Sci Lett 250:561–571ADSCrossRefGoogle Scholar
  29. Parker EN (1958) Dynamics of the interplanetary gas and magnetic fields. ApJ 128:664ADSCrossRefGoogle Scholar
  30. Pillitteri I, Maggio A, Micela G et al (2015) FUV variability of HD 189733. Is the star accreting material from its hot Jupiter? ApJ 805:52Google Scholar
  31. Poppenhaeger K, Schmitt JHMM (2011) A correlation between host star activity and planet mass for close-in extrasolar planets? ApJ 735:59ADSCrossRefGoogle Scholar
  32. Poppenhaeger K, Robrade J, Schmitt J (2010) Coronal properties of planet-bearing stars. Astron Astrophys 515:A98ADSCrossRefGoogle Scholar
  33. Poppenhaeger K, Lenz LF, Reiners A, Schmitt JHMM, Shkolnik E (2011) A search for star-planet interactions in the υ Andromedae system at X-ray and optical wavelengths. Astron Astrophys 528:A58+Google Scholar
  34. Preusse S, Kopp A, Büchner J, Motschmann U (2005) Stellar wind regimes of close-in extrasolar planets. Astron Astrophys 434:1191–1200ADSCrossRefGoogle Scholar
  35. Preusse S, Kopp A, Büchner J, Motschmann U (2006) A magnetic communication scenario for hot jupiters. Astron Astrophys 460:317–322ADSCrossRefGoogle Scholar
  36. Preusse S, Kopp A, Büchner J, Motschmann U (2007) MHD simulation scenarios of the stellar wind interaction with Hot Jupiter magnetospheres. Plant Space Sci 55:589–597ADSCrossRefGoogle Scholar
  37. Saur J, Neubauer FM, Strobel DF, Summers ME (1999) Three-dimensional plasma simulation of Io’s interaction with the Io plasma torus: asymmetric plasma flow. J Geophys Res 104(A11):25,105–25,126ADSCrossRefGoogle Scholar
  38. Saur J, Grambusch T, Duling S, Neubauer FM, Simon S (2013) Magnetic energy fluxes in sub-Alfvénic planet star and moon planet interactions. Astron Astrophys 552:A119. doi:10.1051/0004-6361/201118179ADSCrossRefGoogle Scholar
  39. Scharf CA (2010) Possible constraints on exoplanet magnetic field strengths from planet-star interaction. Astrophys J 722:1547–1555ADSCrossRefGoogle Scholar
  40. Shkolnik E, Walker GAH, Bohlender DA (2003) Evidence for planet-induced chromospheric activity on HD 179949. ApJ 597:1092–1096ADSCrossRefGoogle Scholar
  41. Shkolnik E, Walker GAH, Bohlender DA, Gu P, Kürster M (2005) Hot Jupiters and hot spots: the short- and long-term chromospheric activity on stars with giant planets. ApJ 622:1075–1090ADSCrossRefGoogle Scholar
  42. Shkolnik E, Bohlender DA, Walker GAH, Collier Cameron A (2008) The on/off nature of star-planet interactions. ApJ 676:628–638ADSCrossRefGoogle Scholar
  43. Strugarek A (2016) Assessing magnetic torques and energy fluxes in close-in star-planet systems. ApJ 833:140ADSCrossRefGoogle Scholar
  44. Strugarek A, Brun AS, Matt SP, Réville V (2015) Magnetic games between a planet and its host star: the key role of topology. ApJ 815:111ADSCrossRefGoogle Scholar
  45. Vidotto AA, Fares R, Jardine M, Moutou C, Donati JF (2015) On the environment surrounding close-in exoplanets. MNRAS 449:4117–4130ADSCrossRefGoogle Scholar
  46. Zarka P (2007) Plasma interactions of exoplanets with their parent star and associated radio emissions. Plant Space Sci 55:598–617ADSCrossRefGoogle Scholar
  47. Zarka P, Treumann RA, Ryabov BP, Ryabov VB (2001) Magnetically-driven planetary radio emissions and applications to extrasolar planets. Astrophys Space Sci 277:293–300ADSCrossRefGoogle Scholar

Copyright information

© Springer International Publishing AG 2017

Authors and Affiliations

  1. 1.Institute of Geophysics and MeteorologyUniversity of CologneCologneGermany

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